An atom probe device is an apparatus that ionizes and evaporates atoms on a sample surface by applying a voltage and/or a laser beam to the sample, and that performs a material analysis on the sample at an atomic level by detecting ions using a mass detector. The atom probe device identifies a mass-to-charge ratio of each ion by measuring a flight time of the ion from the sample to the mass detector. The atom probe device thereby discriminates the atoms constituting the sample from one another. Furthermore, the atom probe device identifies relative positions of the respective atoms present on the sample by measuring a position at which each ion hits the mass detector.
However, molecular ions or multi-charged ions are generated at the time of ionization of the atoms present on the sample. Therefore, different types of a plurality of ions sometimes show similar mass-to-charge ratios. In such a case, a user discriminates the ions by comparing an isotope ratio in a detection result with a natural isotope ratio of the element and determining whether the former and the latter match each other.
However, when an element contained in the sample is small in amount, the isotope ratio in the detection result is largely dispersed. As a result, the isotope ratio sometimes largely deviates from the natural isotope ratio. In this case, some users doubt whether the element is present and possibly and erroneously determine that the element is not present in the sample. That is, there is a probability that the element actually contained in the sample is erroneously ignored.